Influence of silicon carbide addition on the microstructural development of hot pressed zirconium and titanium diborides

The influences of adding SiC on the microstructure and densification behavior of ZrB2 and TiB2 ceramics, hot pressed at 1850 °C for 60 min under 20 MPa, were investigated. The sintered samples were characterized by SEM, EDS and XRD methods. A fully dense TiB2-based ceramic was obtained by adding 30 vol% SiC. The grain size of ZrB2 or TiB2 matrices in the final microstructures decreased with increasing SiC content. The XRD analyses, microstructural characterization as well as thermodynamical calculations proved the in-situ formation of TiC in the SiC reinforced TiB2-based composites. The interfaces between ZrB2 and SiC grains in the SiC reinforced ZrB2-based composites were free of any impurities or tertiary interfacial phases such as ZrC. This result was consistent with the X-ray diffraction pattern and thermodynamics.